There are several applications for conventional neutron imager/spectrometers. However, all applications revolve around detecting, locating, monitoring, and identifying nuclear material.
Neutrons are, by their nature, resistant to detection, and defy easy imaging and spectroscopy. Detection has mostly been in the form of registering moderated or thermalized neutrons from a fast neutron source. Because one only measures the charged particles produced by a neutron interaction, deducing the properties of the parent neutron is ambiguous, besides being difficult.
Registering moderated neutrons comes without any information about the incident direction or energy. Measuring fast neutrons in a bulk detector provides a compromised energy measurement, but still lacks directional information. A double-scatter telescope pays the penalties of greatly increased complexity and low efficiency by requiring two neutron scatters, but it benefits in the end because the elastic scatter kinematics can be used to constrain the incident velocity vector while simultaneously performing a quality energy measurement.